Conventional systems for X-ray imaging comprise an X-ray source and an area detector placed behind an object to register an image. The main drawback with this setup is its sensitivity to background noise in form of Compton scattered radiation.
As a solution to this, a slot scanning system has been proposed. Such a system is for example known from EP1192479 B1. A slot scanning system described in EP1192479 B1 comprises an X-ray source and a collimator arrangement comprising several collimator structures. Furthermore, the slot scanning system comprises a detector array and compression plates in between for example a breast can be positioned and compressed. The compression plates are transparent to X-rays. One of the collimator structures is positioned on one side of the compression plates, whereas another collimator structure is positioned at the other side of the compression plates. The slots of the collimator structures are matched and in line with the X-ray source so that the X-rays coming straight from the source, without deflections, that will pass one collimator structure, will also pass the other collimator structure and will hit the detector which is positioned in line with the collimator structures and the X-ray source. The collimator structures are positioned on an arm together with the detector. This arm can move the slots relative to the object.
The stage of the movement is computer controlled and equipped with an accurate position reading. While the slots are moving, data from the detector arrays are read out together with the present coordinate according to the position reading. From this information the image is reconstructed.
The scan trajectory described in EP 1192479 B1 can be a circular movement around the X-ray source. The trajectory can also be arranged to refract the beam in a plane parallel with the compression plates, whereby a linear movement of the collimator and detector will be needed. Moreover, due to the circular radiation, the detectors are arranged in a circular carrier, which in case of a linear movement should be arranged in a flat carrier.